Floating breakwater

ABSTRACT

A floating breakwater in which the floating body is formed by housing a floating material as a floating source and a weighting material as a source for increasing weight in a hollow shell composed of a rigid material and provided with a projection on the upper portion. The specific gravity of the floating body is made to be 0.15 - 0.75 owing to the floating material and the weighting material.

United States Patent 1 Tazaki et al.

[ Feb. 11,1975

[ 1 FLOATING BREAKWATER [75] v Inventors: Sadanori Tazaki; Yozo Ishida,both of Tokyo, Japan [73] Assignee: Bridgestone Tire Company, Limited,

Tokyo, Japan 221 Filed: Sept. 18, 1973 21 Appl.No.: 398,368

[30] Foreign Application Priority Data Sept. 19, 1972 Japan 47-107980Sept. 30, 1972 Japan 47-113640 May 9, 1972 Japan 47-54312 [52] US. Cl.61/5 [51] Int. Cl E02b 3/06 [58] Field of Search 9/8 R; 61/1 F, 3, 4, 5;

[56] References Cited UNITED STATES PATENTS 436.644 9/1890 White 61/52,638,695 5/1953 Phillips... .4 9/8 R X 2,658,350 11/1953 Magill 61/53.103200 9/1963 Fulkerson et a1. .1 9/8 R X 3,534,558 10/1970 Bouteillcr61/5 3.791.150 2/1974 Tachii 61/5 Primary ExaminerPaul R. GilliamAssistant E.raminerDavid H. Corbin Attorney, Agent, or FirmSughrue.Rothwell, Mion. Zinn & Macpeak [57] ABSTRACT A floating breakwater inwhich the floating body is formed by housing a floating material as-afloating source and a weighting material as a source for increasingweight in a hollow shell composed of a rigid materialand provided'with aprojection on the upper portion. The specific gravity of the floatingbody is made to be 0.15 0.75 owing to the floating material and theweighting material.

3 Claims, 16 Drawing Figures PATENTEDFEBWQYS I 3.864.920

' sum 02or12 0.50 Specific gravity of floating body lH/ yj 0 01 105,1808110M l/fiflOJZ/l passod PATENTEDFEBW975 I v 'SHEET C30F 12 rPATENTEDFEBWQYE I I 3.864 920 SHEET M12 PATENTEI] FEB] 1 I975.

SHEET GBOF 12 PATENTEBFEBHWE 3.864.920

' SHEET USUF 12 'PATENTED FEB] 1 5 'SHEET. 10% 12 PATENTED FEB l 1 I975SHEET 11 0F 2' PATENTEBFEHI I ms SHEET 120F 12 FLOATING BREAKWATERBACKGROUND or THE INVENTION 1. Field of the Invention The presentinvention relates to a floating breakwater having a very high wavebreaking efficiency, and which is simple, cheap, and short in length.

2. Description of the Prior Art Heretofore, various structures forbreaking waves have been used in order to suppress waves formed in a seasurface or a lake surface, and recently the sea development has becomeimportant and floating breakwaters having a simple structure and anexcellent effectiveness have been highly demanded.

As breakwaters, a breakwater in which a concrete wall and the like arebuilt in sea, a submerged bank or piling up of concrete blocks, such astetrapods has been considered to be effective but in this case, as thedepth to be piled up is larger, the working becomes large and aconspicuous cost is required.

On the other hand, some means wherein floating bodies are floated onsea, have been considered but in these means, the floating bodies aremerely floated on the waves and consequently when the wave length islarger than the length of the floating body, the efficiency for breakingwaves is very poor. In fact, in order to make the ratio of the height ofwave passed through the floating body to the height of wave beforepassing the floating body (abridged as the passed through 7 wave heightratio hereinafter) less than 0.5, it is necessary to make the length ofthe floating body more than one-half of the wave length and when a wavehaving a long wave length and a low frequency is to be broken, it isnecessary to make the length of the floating body very large and arelation of the shape of the floating body to the wave breakingefficiency has not been clearly found and the shape of the floating bodyhas varied.

SUMMARY OF THE INVENTION An object of the present invention is toprovide a floating breakwater having a very excellent wave breakingefficiency which has a simple structure, can be provided at a low cost,and has a ratio of the height of wave passed through the floating bodyto the height of wave before passing the floating body of less than 0.5in a length of the floating body of less than one-half of the wavelength. The inventors have found that the wave breaking efficiency isinfluenced by phase difference, reflection, friction, whirlpool actionof the wave, and the like. When a floating breakwater is set on thewater surface, if the floating body makes the same motion as that ofwave, the wave breaking efficiency is poor and there fore in thefloating breakwater according to the present invention, the specificgravity of the floating body is controlled in order to increase the wavebreaking efficiency due to the phase difference to fix the floating bodyat a constant position near the water level as far as possible and tocontrol the upward and downward motion against the water leveleffectively, and the wave breaking efficiency due to the reflection andfriction is enhanced by providing a projected body on the upper side ofthe floating body.

The present invention relates to a floating breakwater in which thefloating body is formed by housing a floating material as a floatingsource and a weighting material as a source for increasing weight andthe specific gravity of the floating body is made to be 0.15 0.75 owingto the floating material and the weighting material.

The present invention comprises a built-up floating breakwater which canbe easily built-up at a location to be provided and can be producedcheaply, a floating breakwater constructed with a floating body and aplane plate in which a viscosity resistance owing to water is utilizedand the upward and downward motion of the floating body against thewater level is restrained, a floating and submerging type breakwaterprovided with a tube float having an air inlet in the floating body andvarious improved breakwaters.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates curves showing arelation of the shape of the floating body to the passed through waveheight ratio;

FIG. 2 illustrates curves showing a relation of the specific gravity ofthe floating body to the passed through wave height ratio;

FIG. 3 is a plan view of an embodiment of floating breakwater of thepresent invention;

FIG. 4 is a side view showing a partial cross-section of the floatingbreakwater of FIG. 3;

FIG. Sis a partial cross-section showing the connection of the projectedhollow body with the substrate of the floating breakwater of FIG. 3;

FIG. 6 is a front view showing a partial cross-section of the floatingbreakwater of FIG. 3;

FIG. 7 is a perspective view of an embodiment of floating breakwater ofthe present invention;

FIG. 8 is a plan view of the embodiment of FIG. 7;

' FIG. 9 is a side yiew showing a partial cross-section of theembodiment of FIG. 7;

FIG. 10 is a perspective view of an embodiment of floating breakwater ofthe present invention;

FIG. 11 is a plan view of the embodiment of FIG. 10;

FIG. 12 is a side view showing a partial cross-section of the embodimentof FIG. 10;

.FIG. 13 is a cross-sectional side view of an embodiment of floatingbreakwater of the present invention;

FIG. '14 is a side view of an embodiment of floating breakwater of thepresent invention;

FIG. 15 is a side view of an embodiment of floating breakwater of thepresent invention; and

FIG. 16 is a side view of an embodiment of floating breakwater of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A foaming material and aweighting material are charged in a rectangular hollow floating body anda floating body, the upper surface of which is a corrugated form andboth the floating bodies are determined with respect to the influenceupon the wave breaking efficiency and the result is shown in FIG. 1.

Both the floating bodies have a width (b) of 350 mm and a length (l) of500 mm. In FIG. 1, L is a wave length (unit: meter), H (unit: meter) isa height of wave before the wave passes through the floating body and HT(unit: meter) is a height of wave after passing through the floatingbody. The wave breaking efficiency of the floating body is shown by thepassed through wave height ratio (I-lT/I-I), and the smaller the value,the higher is the wave breaking efficiency.

The inventors have made various experiments and found that the lowerportion of the floating body has no relation and when a projected bodyis formed on the upper portion, a high wave breaking efficiency can beobtained and that when the height of the projected body is aboutone-half of the wave height, the wave breaking efficiency is high.

By using a hollow floating body having a projection on the upper surfaceand adjusting the foaming material as the floating source and a sourcefor increasing the weight, a relation of the specific gravity of thefloating body to the passed through wave height ratio is shown in FIG.2.

As seen from FIG. 2, when the specific gravity of the floating body ismore than 0.15, the upward and downward motion of the floating body inthe water level is prevented effectively and the wave breakingefficiency is considerably high and when the specific gravity is morethan 0.75, there is no particular significance.

Accordingly, in the present invention an excellent wave breakingefficiency can be obtained by adjusting the specific gravity to 0.150.75.

One embodiment of the floating breakwaters of the present invention willbe explained with reference to FIGS. 3, 4, and 6. A floating body 1 ismade of rigid materials, such as metal, concrete, fiberglass reinforcedplastic and the like, and is composed of a projected hollow body 2, asubmerged body 3 and a laminated substrate 4. The laminated substrate 4is composed of two water resistant plates, each of which has fiberglassreinforced plastic coatings on the upper and lower surfaces, and afoamed material inserted between the plates. One or more projectedhollow bodies 2, 2, 2", etc., which extend in a direction perpendicularto the direction of wave, are fixed to the upper surface of thelaminated substrate 4 and one or more submerged bodies 3, 3', 3", etc.,which extend in a direction perpendicular to the direction of theprojected hollow bodies, are fixed to the lower surface of the laminatedsubstrate 4. The projected hollow body and submerged body are producedby bending a water resistant plate 5 having fiberglass reinforcedplastic coating on the upper and lower surfaces in the form of a gutterhaving a trapezoidal (FIGS. 3, 4 and 6) or semicircular cross-sectionalshape. The flange 6 of the gutter is fixed to the laminated substrate 4together with a holding plate 7 or 7' by means of bolts 8 or adhesive(not shown).

The interior of the projected hollow body is empty or filled at leastpartly with synthetic resin foam 9. The interior of the submerged bodyis empty or filled at least partly with water or with materials having aspecific gravity larger than water, such as earth and sand, concrete,iron block and the like.

Alternatively, water holes 10 may be made in the wall of the submergingbody so that water can enter into the submerging body when the floatingbody 1 is arranged in the water level.

When the floating body 1 is arranged on the water level, the body 1 isfixed by connecting rope or chain 12 to holes 11 formed in the front andrear edges of the body 1 and to anchor 13 so that'the projected hollowbodies 2, 2', 2", etc. extend in a direction perpendicular to thedirection of wave.

The submerged bodies 3, 3', 3", etc. are fixed to the laminatedsubstrate 4 in a direction perpendicular to the direction of theprojected hollow bodies 2, 2, 2", etc., in order to reinforce thelaminated substrate 4, which bonds the projected hollow bodies 2, 2, 2",etc. with each other; along the direction of wave.

The cross-sectional shapes of the projected hollow body and thesubmerging body may be trapezoid as shown in the figures, semicircle,rectangle, triangle and other optional shapes. However, when the heightof the projected hollow body is about one-half of the wave height, abest wave breaking efficiency can be attained.

In the present invention, the specific gravity of the floating body 1,which is determined from the amount of water or the weight of fillercontained as a weighting material in the interior of the submergingbodies 3, 3', 3", etc., and the volume of the projected hollow bodies 2,2, 2", etc., or the amount of foam contained as a floating material inthe projected hollow bodies 2, 2', 2", etc., is selected within therange of 0.15 0.75.

When the specific gravity of the floating body 1 is within the abovedescribed range, any type of floating body 1 having projections on thesurface thereof can attain the object of the present invention.

FIGS. 7, 8 and 9 show another embodiment of the floating breakwaters ofthe present invention. In this floating breakwater, a floating body 1 iscomposed of a projected hollow body 15, a submerged body 16 and abonding element 17 which bonds the bodies 15 and 16 with each other. Thebonding element 17 is made into a cylindrical shape and is closedtightly at both ends. The interior of the bonding element 17 is filledwith water up to about half of the volume. The interior of the bondingelement 17 may be filled at least partly with materials having aspecific gravity larger than water, such as earth and sand, concrete,iron block and the like.

The interior of the projected hollow body 15 is empty or filled at leastpartly with synthetic resin foam 9. The interior of the submerging body16 is filled at least partly with water or with earth and sand,concrete, iron block and the like, as described in the case of thebonding element 17. When the projected hollow body 15 and the submergingbody 16 are made so as to envelop the bonding element 17, thecross-sectional shapes of the bodies 15 and 16 may be trapezoid,semicircle, rectangle, triangle and other optional shapes. However, whenthe height of the projected hollow body 15 is about one-half of the waveheight, a best wave breaking efficiency can be attained.

When the floating breakwater shown in FIGS. 7, 8 and 9 is assembled, aplurality of the projected hollow bodies 15 and a plurality of thesubmerged bodies 16 are bonded through a plurality of the bondingelements 17 arranged in parallel so that a plurality of the bondedbodies are arranged in parallel and are perpendicular to the directionof wave. Further, the projected hollow body 15 and the submerging body16 may be divided into unit bodies 15, 15", 15", etc., and 16', 16",16", etc. respectively. The bonding of the projected hollow body 15 withthe submerging body 16, or the bonding of the unit projected hollowbodies 15', 15", 15", etc. with unit submerging bodies 16, 16", 16",etc., is effected by a most suitable means, such as bolts and adhesive,depending upon the properties of the projected hollow body 15, thesubmerging body 16 and the bonding element 17. The bonding portion ofthe adjacent unit bonded bodies, each of which is composed of units 15and 16, 15" and 16'', etc., and the bonding portion of the bondingelement 17 with the projected hollow body and the submerging body 16 maybe provided with seal or packing.

Furthermore, when adjacent projected hollow bodies 15 are kept apartfrom each other, and a floating body 1 is assembled so as to form aspace 14 as shown in FIG. 8, whirlpool of wave occurs in the space 14,and a more improved wave breaking efficiency can be attained.

In the floating breakwater shown in FIGS. 10, 11 and 12, a floating body1 is composed of a plurality of cylindrical shells 18 arranged inparallel and a plurality of cylindrical bonding elements 17 whichpenetrate through the cylindrical shells 18 and bond the shells 18 witheach other. The floating body 1 is arranged so that the shells 18 arearranged in parallel and are perpendicular to the direction of wave.

The cylindrical shell 18 is closed at both ends 18a. Into the interiorof the cylindricalshell 18 were put a floating material 9 as a floatingsource of the floating body 1 and a weighting material 19 as a sourcefor in creasing the weight of the floating body 1, whereby the specificgravity of the floating body 1 is increased and the up-and-down motionof the floating body 1 on the water level is effectively controlled.

I-Ioles are formed in the wall of the shell 18 in order to pass thebonding element 17 through the shell 18, and the shell 18 is providedwith seal or packing at the bonding portion of the holes and the bondingelement 17. Alternatively, the shell 18 may be provided with tubes 18bin the interior thereof. in order to insert the bonding element 17 intothe tubes 18b.

In the floating breakwater of the present invention, as the floatingmaterial 9 to be used as a floating source of the floating body I,mention may be made of foams of polyurethane, polystyrene, polyethylene,polypropylene, polyamide and the like, and gases, such as air and thelike. When air is used as a floating material 9, it is necessary to forma cavity in the interior of the floating body 1 or to arrange a tightlyclosed air room therein.

As the weighting material 19 to be used as a source for increasing theweight of the floating body 1, mention may be made of liquids, such aswater and the like, earth and sand, concrete, iron block and the like.

In general, when it is intended to arrange the floating breakwater onthe sea, it is often required that the floating breakwater is arrangedat a position, which is a passage of ships for a certain period of time.In this case, the floating breakwater must be removed when ships passthe position. Further, if it is intended to adopt such a mooring methodthat the floating breakwater is floated when an extraordinary large waveis generated due to the typhoon, a very high mooring strength isrequired.

FIG. 13 shows an improved floating breakwater of the present invention.This floating breakwater is an up-and-down type breakwater which can befreely floated and sunk and can solve inexpensively the above describeddrawbacks by a very simple structure.

Referring to FIG. 13, a tubular float 22 having an airinlet 21 connectedto a compressed air source through a flexible pipe 20, one end of whichalways floats at a certain position on the water level, is inserted intoa floating body 1. This float 22 acts as a floating element,

and air is charged into or discharged from the float 22 to float or sinkthe floating body 1. In FIG. 13, the numeral 23 represents a buoy whichserves to float always one end of the flexible tube 20 on the waterlevel, the numeral 24 represents the cock of the flexible tube 20 andthe numeral 25 represents a ship provided with a pump.

The rotary motion of wave becomes smaller according to the hyperbolicfunction as the depth of the wave from the water level is larger. Whenthe rotary motion of wave under the water level is disturbed to decreasethe movement of the floating body 1, the wave breaking efflciency of thefloating body I having the above described structure and shape can bemore improved.

In the floating breakwater shown in FIG. 14, the wave breakingefficiency is improved by disturbing the above described rotary motionof wave under the water level. A net bag 27 containing a plurality ofsolid blocks 26 having a wave breaking efflciency is hung under afloating body 1.

Since the floating breakwater of the present inven' tion is located at acertain position near the water level, the floating breakwater has animproved wave breaking efficiency. In the floating breakwaters shown inFIGS. 15 and 16, plates 28 are fixed to a floating body 1 by means ofrigid supports 29, whereby the plate 28 is subjected to a viscosityresistance due to water and the upand-down motion of the floating body 1against the water level is more effectively controlled.

Further, as shown in FIG. 16, when an enclosed space is formed between afloating body 1 and a plate 28, and blocks composed of metal, concrete,plastic, etc. are put into the space to disturb the rotary motion ofwave under the water level, a more improved wave breaking efficiency canbe attained.

What is claimed is:

l. A floating breakwater assembly, comprising:

a. a plurality of substantially equally dimensioned, elongated, floatingbodies each comprising a rigid hollow upper shell and a rigid hollowlower shell bonded together, each upper shell projecting upwardly andout of the water along its entire length to a height of at least onehalf of the average height of waves to be broken,

b. floatation material within each hollow upper shell,

0. ballast material within each hollow lower shell whereby the latterare submerged,

d. a plurality of spaced, elongated, rigid cylindrical members extendingtransversely of and between the floating bodies for bonding themtogether in a spaced assembly,

e. means for mooring the assembly to the sea bottom such that thefloating bodies are generally perpendicular to the direction of movementofwaves to be broken, and

f. the specific gravity of the overall assembly being from 0.15 to 0.75.

2. The floating breakwater as claimed in claim 1,

0 wherein said floatation material is a synthetic resin foam.

3. The floating breakwater as claimed in claim 1,

wherein said ballast material is water.

1. A floating breakwater assembly, comprising: a. a plurality ofsubstantially equally dimensioned, elongated, floating bodies eachcomprising a rigid hollow upper shell and a rigid hollow lower shellbonded Together, each upper shell projecting upwardly and out of thewater along its entire length to a height of at least one half of theaverage height of waves to be broken, b. floatation material within eachhollow upper shell, c. ballast material within each hollow lower shellwhereby the latter are submerged, d. a plurality of spaced, elongated,rigid cylindrical members extending transversely of and between thefloating bodies for bonding them together in a spaced assembly, e. meansfor mooring the assembly to the sea bottom such that the floating bodiesare generally perpendicular to the direction of movement of waves to bebroken, and f. the specific gravity of the overall assembly being from0.15 to 0.75.
 2. The floating breakwater as claimed in claim 1, whereinsaid floatation material is a synthetic resin foam.
 3. The floatingbreakwater as claimed in claim 1, wherein said ballast material iswater.